Most of the University of California Berkeley campus has regained power after an overnight explosion blacked out campus buildings.

The explosion sent one person to the hospital with burns and forced the evacuation of the entire campus Monday night.

“The explosion was about two stories high and as wide as a two-lane street,” UC Berkeley spokesman Dan Mogulof told reporters. “We’re very fortunate there were no serious injuries.”‘

The explosion was part of a night of chaos on the campus. The power initially went out at 4:30 p.m. trapping 20 people in elevators who had to be rescued by fire crews. Then an ammonia leak was discovered in one science hall that was quickly contained followed by the explosion in an underground utility vault.

The blast is suspected to be caused by a theft of copper wire from the underground vault. The damage to the vault was more extensive than initially believed and led to the explosion during a repair attempt.